Thick Does the Trick: Genesis of Ferroelectricity in 2D GeTe-Rich (GeTe)_m (Sb₂ Te₃ )_n Lamellae.

ABSTRACT: The possibility to engineer (GeTe)_m (Sb₂ Te₃ )_n phase-change materials to co-host ferroelectricity is extremely attractive. The combination of these functionalities holds great technological impact, potentially enabling the design of novel multifunctional devices. Here an experimental and theoretical study of epitaxial (GeTe)_m (Sb₂ Te₃ )_n with GeTe-rich composition is presented. These layered films feature a tunable distribution of (GeTe)_m (Sb₂ Te₃ )₁ blocks of different sizes. Breakthrough evidence of ferroelectric displacement in thick (GeTe)_m (Sb₂ Te₃ )₁ lamellae is provided. The density functional theory calculations suggest the formation of a tilted (GeTe)_m slab sandwiched in GeTe-rich blocks. That is, the net ferroelectric polarization is confined almost in-plane, representing an unprecedented case between 2D and bulk ferroelectric materials. The ferroelectric behavior is confirmed by piezoresponse force microscopy and electroresistive measurements. The resilience of the quasi van der Waals character of the films, regardless of their composition, is also demonstrated. Hence, the material developed hereby gathers in a unique 2D platform the phase-change and ferroelectric switching properties, paving the way for the conception of innovative device architectures.

SUBMITTER: Cecchi S 

PROVIDER: S-EPMC10767439 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature